Nowadays, you do not have to worry too much about installing OpenSSL: most distributions use package management applications. Refer to your distribution documentation, or read the README and INSTALL file inside the OpenSSL tarball. I want also to avoid to make this HOWTO, an installation HOWTO rather than an HOWTO use certificates.

I describe here some standard installation options which are necessary to know for the samples following. Your installation may differ.

The directory for all OpenSSL certificates is /var/ssl/. All commands and paths in this document are issued from this directory, it is not mandatory but it will help the examples.

OpenSSL by default looks for a configuration file in /usr/lib/ssl/openssl.cnf so always add -config /etc/openssl.cnf to the commands openssl ca or openssl req for instance. I use /etc/openssl.cnf so all my configuration files are all in /etc.

Ensure that the utility CA.pl is in an accessible directory such as /usr/sbin. CA.pl can be found inside /usr/lib/ssl directories. CA.pl is a utility that hides the complexity of the openssl command. In all the examples, when I use CA.pl, I will also put the openssl equivalent in brakets.

/usr/sbin/CA.pl needs to be modified to include -config /etc/openssl.cnf in ca and req calls.

/etc/openssl.cnf must be configured accordingly to minimize input entry.

#---Begin---
#
# OpenSSL example configuration file.
# This is mostly being used for generation of certificate requests.
#
RANDFILE = $ENV::HOME/.rnd
oid_file = $ENV::HOME/.oid
oid_section = new_oids
# To use this configuration file with the "-extfile" option of the
# "openssl x509" utility, name here the section containing the
# X.509v3 extensions to use:
# extensions =
# (Alternatively, use a configuration file that has only
# X.509v3 extensions in its main [= default] section.)
[ new_oids ]
# We can add new OIDs in here for use by 'ca' and 'req'.
# Add a simple OID like this:
# testoid1=1.2.3.4
# Or use config file substitution like this:
# testoid2=${testoid1}.5.6
####################################################################
[ ca ]
default_ca = CA_default # The default ca section
####################################################################
[ CA_default ]
dir = /var/ssl # Where everything is kept
certs = $dir/certs # Where the issued certs are kept
crl_dir = $dir/crl # Where the issued crl are kept
database = $dir/index.txt # database index file.
new_certs_dir = $dir/newcerts # default place for new certs.
certificate = $dir/cacert.pem # The CA certificate
serial = $dir/serial # The current serial number
crl = $dir/crl.pem # The current CRL
private_key = $dir/private/cakey.pem # The private key
RANDFILE = $dir/private/.rand # private random number file
x509_extensions = usr_cert # The extentions to add to the cert
# Extensions to add to a CRL. Note: Netscape communicator chokes on V2 CRLs
# so this is commented out by default to leave a V1 CRL.
# crl_extensions = crl_ext
default_days = 365 # how long to certify for
default_crl_days= 7 # how long before next CRL
default_md = sha1 # which md to use.
preserve = no # keep passed DN ordering
# A few difference way of specifying how similar the request should look
# For type CA, the listed attributes must be the same, and the optional
# and supplied fields are just that :-)
policy = policy_match
# For the CA policy
[ policy_match ]
countryName = match
stateOrProvinceName = optional
localityName = match
organizationName = match
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
# For the 'anything' policy
# At this point in time, you must list all acceptable 'object'
# types.
[ policy_anything ]
countryName = optional
stateOrProvinceName = optional
localityName = optional
organizationName = optional
organizationalUnitName = optional
commonName = supplied
emailAddress = optional
####################################################################
[ req ]
default_bits = 1024
default_keyfile = privkey.pem
distinguished_name = req_distinguished_name
attributes = req_attributes
default_md = sha1
x509_extensions = v3_ca # The extentions to add to the self signed cert
# Passwords for private keys if not present they will be prompted for
# input_password = secret
# output_password = secret
# This sets a mask for permitted string types. There are several options.
# default: PrintableString, T61String, BMPString.
# pkix : PrintableString, BMPString.
# utf8only: only UTF8Strings.
# nombstr : PrintableString, T61String (no BMPStrings or UTF8Strings).
# MASK:XXXX a literal mask value.
# WARNING: current versions of Netscape crash on BMPStrings or UTF8Strings
# so use this option with caution!
string_mask = nombstr
# req_extensions = v3_req # The extensions to add to a certificate request
[ req_distinguished_name ]
countryName = Country Name (2 letter code)
countryName_default = FJ
countryName_min = 2
countryName_max = 2
stateOrProvinceName = State or Province Name (full name)
stateOrProvinceName_default = Fiji
localityName = Locality Name (eg, city)
localityName_default = Suva
0.organizationName = Organization Name (eg, company)
0.organizationName_default = SOPAC
# we can do this but it is not needed normally :-)
#1.organizationName = Second Organization Name (eg, company)
#1.organizationName_default = World Wide Web Pty Ltd
organizationalUnitName = Organizational Unit Name (eg, section)
organizationalUnitName_default = ITU
commonName = Common Name (eg, YOUR name)
commonName_max = 64
emailAddress = Email Address
emailAddress_max = 40
# SET-ex3 = SET extension number 3
[ req_attributes ]
challengePassword = A challenge password
challengePassword_min = 4
challengePassword_max = 20
unstructuredName = An optional company name
[ usr_cert ]
# These extensions are added when 'ca' signs a request.
# This goes against PKIX guidelines but some CAs do it and some software
# requires this to avoid interpreting an end user certificate as a CA.
basicConstraints=CA:FALSE
# Here are some examples of the usage of nsCertType. If it is omitted
# the certificate can be used for anything *except* object signing.
# This is OK for an SSL server.
# nsCertType = server
# For an object signing certificate this would be used.
# nsCertType = objsign
# For normal client use this is typical
# nsCertType = client, email
# and for everything including object signing:
# nsCertType = client, email, objsign
# This is typical in keyUsage for a client certificate.
# keyUsage = nonRepudiation, digitalSignature, keyEncipherment
# This will be displayed in Netscape's comment listbox.
nsComment = "Certificate issued by https://www.sopac.org/ssl/"
# PKIX recommendations harmless if included in all certificates.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid,issuer:always
# This stuff is for subjectAltName and issuerAltname.
# Import the email address.
# subjectAltName=email:copy
# Copy subject details
# issuerAltName=issuer:copy
# This is the base URL for all others URL addresses
# if not supplied
nsBaseUrl = https://www.sopac.org/ssl/
# This is the link where to download the latest Certificate
# Revocation List (CRL)
nsCaRevocationUrl = https://www.sopac.org/ssl/sopac-ca.crl
# This is the link where to revoke the certificate
nsRevocationUrl = https://www.sopac.org/ssl/revocation.html?
# This is the location where the certificate can be renewed
nsRenewalUrl = https://www.sopac.org/ssl/renewal.html?
# This is the link where the CA policy can be found
nsCaPolicyUrl = https://www.sopac.org/ssl/policy.html
# This is the link where we can get the issuer certificate
issuerAltName = URI:https://www.sopac.org/ssl/sopac.crt
# This is the link where to get the latest CRL
crlDistributionPoints = URI:https://www.sopac.org/ssl/sopac-ca.crl
[ v3_ca ]
# Extensions for a typical CA
# PKIX recommendation.
subjectKeyIdentifier=hash
authorityKeyIdentifier=keyid:always,issuer:always
# This is what PKIX recommends but some broken software chokes on critical
# extensions.
# basicConstraints = critical,CA:true
# So we do this instead.
basicConstraints = CA:true
# Key usage: this is typical for a CA certificate. However since it will
# prevent it being used as an test self-signed certificate it is best
# left out by default.
# keyUsage = cRLSign, keyCertSign
# Some might want this also
# nsCertType = sslCA, emailCA
# Include email address in subject alt name: another PKIX recommendation
# subjectAltName=email:copy
# Copy issuer details
# issuerAltName=issuer:copy
# RAW DER hex encoding of an extension: beware experts only!
# 1.2.3.5=RAW:02:03
# You can even override a supported extension:
# basicConstraints= critical, RAW:30:03:01:01:FF
# This will be displayed in Netscape's comment listbox.
nsComment = "Certificate issued by https://www.sopac.org/ssl/"
# This is the base URL for all others URL addresses
# if not supplied
nsBaseUrl = https://www.sopac.org/ssl/
# This is the link where to download the latest Certificate
# Revocation List (CRL)
nsCaRevocationUrl = https://www.sopac.org/ssl/sopac-ca.crl
# This is the link where to revoke the certificate
nsRevocationUrl = https://www.sopac.org/ssl/revocation.html?
# This is the location where the certificate can be renewed
nsRenewalUrl = https://www.sopac.org/ssl/renewal.html?
# This is the link where the CA policy can be found
nsCaPolicyUrl = https://www.sopac.org/ssl/policy.html
# This is the link where we can get the issuer certificate
issuerAltName = URI:https://www.sopac.org/ssl/sopac.crt
# This is the link where to get the latest CRL
crlDistributionPoints = URI:https://www.sopac.org/ssl/sopac-ca.crl
[ crl_ext ]
# CRL extensions.
# Only issuerAltName and authorityKeyIdentifier make any sense in a CRL.
# issuerAltName=issuer:copy
authorityKeyIdentifier=keyid:always,issuer:always
#----End----

A few comments on openssl.cnf.

Variable names can use the suffixes _default for default value, _min for the minimum number of characters required and _max for the maximum number of characters required.

The file is composed of [Sections] of variables.

dir:

Specifies the base directory.

default_ca:

Specifies which section contains the variables for a default certificate.

basicConstraints:

Defines the usage of the certificate, for instance with CA:TRUE, the certificate is a root CA Certificate.

To create a certification authority, use the command after correctly editing openssl.cnf:

CA.pl -newca

The utility will ask you to select a certificate file to act as you CA certificate or you are prompted to create one. Follow the steps to create one as exrecise. In the next chapter we will overwrite this default created CA to create a new one with a longer life span. CA.pl creates only 365 days certificates.